Pneumatic motor

ABSTRACT

A pneumatic motor includes a cylinder, a rotor and a drive shaft. The cylinder includes a cylinder body having two ends, a first cover and a second cover. The first cover is mounted on one of the ends of the cylinder body and has a first bearing housing, a first bearing and a first blocking ring. The first bearing is mounted in the first bearing housing and has an annular clearance. The first blocking ring is mounted between the first bearing housing and the first bearing and covers the annular clearance of the first bearing. The rotor is mounted rotatably in the cylinder body. The drive shaft is mounted securely through the rotor. When compressed air is expelled from the cylinder body, the compressed air does not blow lubricants out of the first bearing because the first blocking ring closes the annular clearance.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a motor, and more particularly to apneumatic motor that can prevent bearing lubricant from being blown out.

2. Description of the Related Art

A conventional pneumatic motor is used for pneumatic tools such as apneumatic sanding device, a pneumatic screwdriver and a pneumaticwrench. With reference to FIG. 3, a pneumatic sanding device comprises abody (60), a conventional pneumatic motor and a sanding pad (91). Thepneumatic motor is mounted in the body (60) and comprises a cylinder, arotor (80) and a drive shaft (90). The cylinder comprises a cylinderbody (71), a first cover (72) and a second cover (73). The cylinder body(71) has two ends and a receiving space. The first and second covers(72, 73) are mounted respectively on the ends of the cylinder body (71)and each has a bearing housing (731) and a bearing (721, 732) mounted inthe bearing housing (731). The rotor (80) is mounted rotatably in thereceiving space of the cylinder body (71) and has multiple blades (81)attached and protruding therefrom. The drive shaft (90) is securelymounted through to the rotor (80). The sanding pad (91) is mountedeccentrically on the drive shaft (90).

The pneumatic sanding device is driven by compressed air to rotate therotor (80) and the drive shaft (90) so that the sanding pad (91) isrotated eccentrically for sanding. However, when the compressed air isexpelled from the cylinder body (71), the compressed air may passthrough the bearings (721, 732) on the cylinder body (71) and blowlubricants out of the bearings (721, 732). Bearings (721, 732) withoutlubricant will seriously wear the bearings (721, 732), shortening lifespan of the bearings (721, 732) and may cause critical failure of theconventional pneumatic motor.

To overcome the shortcomings, the present invention provides a pneumaticmotor to mitigate or obviate the aforementioned problems.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide a pneumaticmotor that can prevent bearing lubricant from being blown out.

A pneumatic motor in accordance with the present invention comprises acylinder, a rotor and a drive shaft. The cylinder comprises a cylinderbody, a first cover and a second cover. The cylinder body has two endsand a receiving space. The first cover is mounted on one of the ends ofthe cylinder body and has a first bearing housing, a first bearing and afirst blocking ring. The first bearing is mounted in the first bearinghousing and has an inner race, an outer race and an annular clearance.The outer race is disposed around the inner race. The annular clearanceis defined between the inner race and the outer race. The first blockingring is mounted between the first bearing housing and the first bearingand covers the annular clearance of the first bearing. The second coveris mounted on the other end of the cylinder body.

The rotor is mounted rotatably in the receiving space of the cylinderbody and has multiple blades. The drive shaft is mounted securelythrough the rotor.

Other objectives, advantages and novel features of the invention willbecome more apparent from the following detailed description when takenin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially exploded perspective view of a pneumatic motor inaccordance with the present invention;

FIG. 2 is an enlarged side view in partial section of the pneumaticmotor in FIG. 1; and

FIG. 3 is a partially exploded perspective view of a pneumatic motor inaccordance with the prior art.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIGS. 1 and 2, a pneumatic motor in accordance withthe present invention comprises a cylinder (10), a rotor (20) and adrive shaft (30). The cylinder (10) comprises a cylinder body (11), afirst cover (12) and a second cover (13). The cylinder body (11) has twoends and a receiving space. The first cover (12) is mounted on one ofthe ends of the cylinder body (11) and has a first bearing housing(121), a first bearing (122) and a first blocking ring (123). The firstbearing housing (121) is formed on the first cover (12). The firstbearing (122) is mounted in the first bearing housing (121) and has aninner race (1221), an outer race (1222) and an annular clearance. Theouter race (1222) is disposed around the inner race (1221). The annularclearance is defined between the inner race (1221) and the outer race(1222). The first blocking ring (123) is mounted between the firstbearing housing (121) and the first bearing (122) and covers the annularclearance of the first bearing (122).

The second cover (13) is mounted on the other end of the cylinder body(11) and has a second bearing housing (131), a second bearing (132) anda second blocking ring (133). The second bearing housing (131) is formedon the second cover (13). The second bearing (132) is mounted in thesecond bearing housing (131) and has an inner race (1321) an outer race(1322) and an annular clearance. The outer race (1322) is disposedaround the inner race (1321). The annular clearance is defined betweenthe inner race (1321) and the outer race (1322). The second blockingring (133) is mounted between the second bearing housing (131) and thesecond bearing (132) and covers the annular clearance of the secondbearing (132).

The rotor (20) is mounted rotatably in the receiving space of thecylinder body (11) and has multiple blades (21) protruding from therotor (20) and a keyed through hole. The drive shaft (30) is mountedsecurely through the rotor (20), is connected to the first bearing (122)and the second bearing (132) and may be keyed corresponding to thethrough hole of the rotor (20). A sanding pad (31) is further mountedeccentrically on the drive shaft (30) so that the pneumatic motor can beused for a pneumatic sanding device.

When compressed air enters the cylinder body (11) and drives the blades(21) of the rotor (20), the rotor (20) is rotated to force the driveshaft (30) to rotate. When the compressed air is expelled from thecylinder body (11) the compressed air does not pass through the firstand second bearings (122, 132) of the cylinder body (11) because theannular clearances of the first and second bearings (122, 132) arecovered and closed by the blocking rings (123, 133). Therefore, thecompressed air does not blow lubricants out of the first and secondbearings (122, 132). The first and second bearings (122, 132) can worksmoothly within expected life span. A durability of the pneumatic motoris therefore maintained.

The pneumatic motor in accordance with the present invention shown in apneumatic sanding device is for example only and may be equally appliedin other pneumatic tools such as a pneumatic screwdriver, a pneumaticwrench or the like wherein the drive shaft (30) is mounted to achangeable head, socket or the like.

Even though numerous characteristics and advantages of the presentinvention have been set forth in the foregoing description, togetherwith details of the structure and function of the invention, thedisclosure is illustrative only. Changes may be made in detail,especially in matters of shape, size and arrangement of parts within theprinciples of the invention to the full extent indicated by the broadgeneral meaning of the terms in which the appended claims are expressed.

1. A pneumatic motor comprising a cylinder comprising a cylinder bodyhaving two ends and a receiving space; a first cover being mounted onone of the ends of the cylinder body and having a first bearing housingbeing formed on the first cover; a first bearing being mounted in thefirst bearing housing and having an inner race; an outer race beingdisposed around the inner race; and an annular clearance being definedbetween the inner race and the outer race; and a first blocking ringbeing mounted between the first bearing housing and the first bearingand covering the annular clearance of the first bearing; and a secondcover being mounted on the other end of the cylinder body; a rotor beingmounted rotatably in the receiving space of the cylinder body and havingmultiple blades protruding from the rotor; and a drive shaft beingmounted securely through the rotor and connected to the first bearing.2. The pneumatic motor as claimed in claim 1, herein the second coverhas a second bearing housing being formed on the second cover; a secondbearing being mounted in the second bearing housing, being mountedaround the drive shaft and having an inner race; an outer race beingdisposed around the inner race, and an annular clearance being definedbetween the inner race and the outer race; and a second blocking ringbeing mounted between the second bearing housing and the second bearingand covering the annular clearance of the second bearing.
 3. Thepneumatic motor as claimed in claim 2, wherein a sanding pad is furthermounted eccentrically on the drive shaft.
 4. The pneumatic motor asclaimed in claim 1, wherein a sanding pad is further mountedeccentrically on the drive shaft.